Fuel injection nozzle units



March 10, 1964 F. M. EVANS 3,124,305

FUEL INJECTION NOZZLE UNITS Filed June 9, 1961 b 5171747 47 1 +4 451 H 6 728 M a U L 45 |2 3 40 U 5 United States Patent 3,124,305 FUEL INJECTION NOZZLE UNITS Fraser Mackie Evans, Ickenham, Uxbridge, England, assignor to C.A.V. Limited, London, England Filed June 9, 1961, Ser. No. 116,163 1 Claim. (Cl. 239533) This invention relates to fuel injection nozzle units of the kind comprising a hollow body, a nozzle at one end of the body, a chamber in the nozzle adjacent the outlet orifice, a fuel inlet at one side of the body, passages in the body and nozzle through which the inlet is in communication with said chamber, a plunger in the nozzle extending into the chamber, said plunger having a stem extending into the body, and a spring acting between the stem and a relatively fixed abutment in the body to load the plunger against a seating surrounding the outlet, the arrangement being such that the plunger is moved away from the seating against the action of the spring by the pressure of fuel in the chamber when said pressure exceeds a predetermined value.

The object of the present invention is to provide a unit of the aforesaid kind in a convenient form.

According to the invention in a fuel injection nozzle unit of the kind specified the abutment is constituted by a separately formed cylindrical part inserted as an interference fit within an open end of the body.

An example of the invention is illustrated in sectional side elevation in the accompanying drawing.

Referring to the drawing, there is provided a hollow body 1 of stepped cylindrical form. The smaller end of this body is externally screw threaded and has secured thereto a hollow stepped cylindrical nozzle 2, the wider end of the nozzle 2 being held against the body 1 by means of an internally screw threaded cap 3 having a central hole through which the narrower part of the nozzle extends.

At one side of the body is a fuel inlet 4 adapted for connection to a fuel pump. The inlet 4 is in communication, through a passage 5 in the body, with a concentric annular groove 6 formed in the end face of the nozzle 2 which is held against the body. The groove 6 is in communication through an eccentric passage 7 in the nozzle with a chamber 8 from which extends the centrally disposed outlet orifice 9 at the outer end of the nozzle.

In an axial cylindrical bore in the nozzle 2 is accommodated a plunger 10. The outer end of this plunger is of conical form and is adapted to seat against a seating surrounding the outlet orifice 9. At the inner end of the plunger is a stem 11 which extends into the body. The stem has a neck 12 adjacent the plunger and is accommodated in a restricted part of the bore in the body, whilst at the inner end of the stem is a head 13 which serves as an abutment for one end of a coiled compression spring 14. The opposite end of the coiled compression spring bears against a relatively fixed abutment 15. The latter takes the form of a cylindrical plug inserted as an interference fit within the open inner end of the body. Moreover, in the plug is a central passage 16 through which any fuel which seeps past the plunger into the body can escape, the passage 16 being internally screw-threaded at its outer end for engagement by a tool 17 whereby the setting of the plug can be adjusted.

The arrangement is such that the compression spring 14 normally holds the plunger 16 against its seating and thereby prevents escape of fuel from the outlet 9. However, when the pressure of fuel in the chamber reaches a predetermined value its action upon the annular face of the plunger 10 causes the latter to be moved inwardly against the action of the spring 14 and thereby allow fuel to be injected to the engine.

It will be appreciated that the degree of compression of the spring determines the predetermined pressure at which the plunger will be removed from its seating, and that this compression of the spring is determined by the setting of the plug 15 in the body.

The tool 17 comprises a stepped-cylindrical screw 17 the narrower end of which is adapted to engage the screwthreaded part of the passage 16. The wider end of the screw carries a handle 17 and engages with a central hole in a cap nut 17 having a rim of a diameter such that it will bear against the adjacent end of the body 1 whilst not over-lapping the plug 15.

After engaging the screw 17 with the plug 15 the pressure of the spring 14 can be reduced by actuating the nut 17 whilst against the body 1 so as to retract the plug. To increase the pressure of the spring the nut 17" is first actuated to provide an estimated clearance between it and the body and the tool is moved axially as, for example, by a hammer blow until the nut 17 again contacts the body.

When the tool 17 is removed the screw thread in the passage 16 may be used for the attachment of a tube to the plug 15, whereby fuel escaping from the body can be conducted to a remote point.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

A fuel injection nozzle unit comprising in combination an elongated body provided with a bore extending longitudinally therethrough, a nozzle which is secured to, and extends from one end of said body, and which is provided with an internal chamber adjacent a fuel outlet orifice in the end of said nozzle remote from said body, a fuel inlet at one side of said body, the latter and said nozzle being provided with passages through which said inlet communicates with said chamber, a plunger slidably mounted in said nozzle, and extending at one end of said plunger into the bore in said body, a cylindrical abutment having an interference fit within the end portion of said bore remote from said nozzle so that said abutment is axially adjustable relative to said body, but is retainable in its adjusted positions by said interference fit, said cylindrical abutment having a coaxial and screw-threaded hole and a compression spring arranged between said abutment and said stern for urging said plunger into a position in which it closes the fuel outlet orifice in said nozzle, said plunger being movable against the action of said spring, to open said fuel outlet orifice, by the pressure of fuel admitted to said chamber from said inlet when said pressure is sufliciently high.

References Cited in the file of this patent UNITED STATES PATENTS 

